The present invention relates generally to syncnronous motors and the gear trains associated therewith; and more particularly, to a means and method of holding the two together.
A multitude of applications for synchronous motors of the type using a permanent magnet rotor are known. Such applications include, for example, a drive means for timing devices such as electric clocks and the like, and as a drive means for sequence timers, such as the type used with washing machines, dishwashers, dryers and the like.
The synchronous motor has a high R.P.M. output which must be reduced significantly if the motor is to be used with the sequence timer. The generally accepted practice is to reduce the output speed of the motor by interposing the gear reduction means between the output of the motor and the input of the sequence timer. In some type of constructions, the gear train cooperatively associated with the motor is incorporated within the housing retaining the motor. With this type of construction, it may be necessary to replace the entire motor assembly if any one of the gear teeth of the gear train becomes crowned or reaches the end of its useful life through some type of failure. In addition, if a different output speed is required, it would be entirely possible that the entire motor assembly would need to be replaced rather than merely replacing the inexpensive gear train.
To this end, the art has, in recent years, enclosed a synchronous motor and the gear train in separate housings. This type of construction leads to the problem of holding the two housings together such that the motor pinion is always in ecact alignment with the first gear or pinion of the gear train. Futhermore, a holding means should be of some a construction that the gear train is easily disconnected from the housing of the motor such that the output speed can be readily changed.
In U.S. Pat. No. 3,676,725 there is described and claimed a synchronous motor and gear train wherein the motor and gear train are carried in separate housings. The housings are held together through tabs extending from the motor housing and engaging apertures in the gear train housing. While this arrangement has been found to be quite satisfactory, it does have the disadvantage of being limited to the particular motor and gear train size; that is, various sizes of motors and gear trains are not readily interchangeable.